PCA9548APW

The PCA9548A device has eight bidirectional
translating switches that can be controlled through
the I2C bus. The SCL/SDA upstream pair fans out to
eight downstream pairs, or channels. Any individual
SCx/SDx channel or combination of channels can
be selected, determined by the contents of the
programmable control register. These downstream
channels can be used to resolve I2C slave address
conflicts. For example, if eight identical digital
temperature sensors are needed in the application,
one sensor can be connected at each channel: 0-7.
The system master can reset the PCA9548A in the
event of a time-out or other improper operation by
asserting a low in the RESET input. Similarly, the
power-on reset deselects all channels and initializes
the I2C/SMBus state machine. Asserting RESET
causes the same reset and initialization to occur
without powering down the part. This allows recovery
should once of the downstream I2C buses get stuck in
a low state.
The pass gates of the switches are constructed so
that the VCC pin can be used to limit the maximum
high voltage, which is passed by the PCA9548A.
This allows the use of different bus voltages on
each pair, so that 1.8-V, 2.5-V or 3.3-V parts can
communicate with 5-V parts, without any additional
protection. External pull-up resistors pull the bus up to
the desired voltage level for each channel. All I/O pins
are 5-V tolerant.